Ask the Doc

What’s indole-3-carbinol?

This powerful antioxidant is another reason to eat your veggies

Q: What’s indole-3-carbinol?

A: Indole-3-carbinol is one of the many reasons to eat your vegetables. It’s a phytochemical (phyto- meaning “plant”) found in cruciferous vegetables (including broccoli, cauliflower, Brussels sprouts, cabbage and kale). In addition to being a powerful antioxidant, which helps protect all cell structures (including DNA), indole-3-carbinol’s main claim to fame is as an estrogen traffic cop.

Estrogen metabolism is a complex affair. The hormone itself comes in three primary naturally available “flavors” – estrone, estradiol and estriol – and further metabolizes into a variety of compounds with long, formidable names such as 16α-Hydroxyestrone. Some of these compounds are problematic because they’re much more likely to promote the growth of hormone-dependent cancers than other (benign) forms.

Indole-3-carbinol acts as a kind of traffic cop, channeling estrogen metabolism into benevolent pathways and helping to keep it out of the pathways where it may be cancer-promoting.

Both it and its metabolite, DIM (3,3’-Diindolylmethane), have also been shown to inhibit the development of prostate cancer.

There’s no official “minimum daily amount” recommendation for indole-3-carbinol, and it’s difficult to know exactly how much indole-3-carbinol is in each portion of broccoli. But the same can be said of flavanols in cocoa, anthocyanins in blueberries or flavonoids in apples. The point is, indole-3- carbinol is a good thing to get in your diet and an excellent reason to feature cruciferous vegetables on your plate at least once a day.

Both indole-3-carbinol and its even better-absorbed metabolite DIM are available as supplements, usually at a dose of 200 milligrams per capsule and a serving size of one to two capsules daily. (I’m a DIM fan myself, and that’s what I give to the women in my family, but some health professionals prefer indole-3-carbinol.) If you decide you’d like to supplement, consult with your health professional on the best dose (and best supplement form) for you.